In the related art, devices which are described in Japanese Patent No. 5411459 (Reference 1) and JP2009-90941A (Reference 2) are known as examples of a vehicular seat slide device. These devices are provided with a lower rail, an upper rail which is linked to be movable with respect to the lower rail, a resin nut which is fixed to the lower rail, and a screw rod which is pivotally supported by the upper rail. In addition, when the screw rod is rotated by an electric motor, the screw rod moves with respect to the nut. At this time, as the nut which is related to generation of a driving force in a moving direction is made of resin, it is assumed that generation of noise is suppressed. In addition, when the rotation of the screw rod is stopped, the movement of the screw rod is restricted at a position with respect to the nut at this time. According to this, a position of the upper rail with respect to the lower rail, that is, a position of a seat with respect to a vehicular floor is adjusted.
Incidentally, in Reference 1, by holding the resin nut with a metal cover, for example, strength with respect to a load in an axial line direction which is applied at a time of collision of a vehicle, that is, a load (hereinafter, referred to as a “collision load”) of the upper rail in a moving direction, is ensured. However, it is necessary to ensure a sufficient length in the moving direction in order to ensure strength of a screw hole as the nut itself is made of resin.
Meanwhile, in Reference 2, the resin nut is formed being integrated with a metal case. However, it is also necessary to ensure a sufficient length in the moving direction in order to ensure the strength of the screw hole as the nut itself is made of resin.
Therefore, in any of Reference 1 and Reference 2, it is inevitable that the size of the rail in the moving direction increases, or that a range of adjustment of the rail in the moving direction decreases.